1. Field of the Invention
This invention relates to the field of electronic systems, and in particular to an electronic system with a security co-processor that isolates select blocks from a main processor, thereby isolating the select blocks from a potential compromise of the main processor.
2. Description of Related Art
The need for security systems to protect electronic systems from hackers, and/or the viruses that some hackers produce, continues to increase. In the realm of entertainment systems, hackers have targeted such devices as cable or satellite “converter boxes”, in an attempt to steal the services provided without paying the required access fees. In the realm of computing systems, hackers continually attempt to access and/or modify information in other computers, either directly or via the dissemination of a virus program. As advances are made in home-automation and seamless integration of consumer equipment, the distinction between a “computing system”, an “entertainment system”, an “appliance network”, and so on, will become increasingly blurred, and virtually all or most of one's collection of electronic devices will be susceptible to hackers.
In a typical security system, such as used for preventing access to select content material from a television converter box, a security device, such as a “smart card” is used to authenticate a user's action, such as the purchase of the content material. Typically, the smart card generates a cryptographic key that is communicated to a decryption device that decrypts the content material using this key. Also typically, to allow for modular design practices, the smart card device communicates this key to the decryption device via a common bus, generally under the control of a processor that also controls other functions within the converter box. A corruption of the code used by the processor can compromise the security provided by the smart card, for example, by copying the key and distributing it to users who have not purchased the material.
In other security systems, the security device is isolated from the common bus, and from the common processor. Such systems, however, are generally more costly, requiring direct point-to-point connections, and less versatile, because of the direct connection between particular devices. Also, because these systems are purposefully isolated from the common processor, these systems are generally not well integrated into the common system, often, for example, having a different user interface from the interface provided by the common processor. A common example of such a system is the maintenance systems common on a mainframe computer system, wherein remote diagnostics occur via a secure channel. In the personal computer field, or consumer electronics field, secure coprocessors are used to provide secure processes and procedures, but are purposely provided a minimal interface with the main processor of the computer or consumer device.